焊接工艺参数对9Ni钢焊接接头组织及弯曲性能的影响
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摘要
在保证小热输入的前提下,采用不同的焊接工艺参数对9Ni钢进行焊条电弧焊,观察焊接接头金相组织,并对接头进行拉伸、硬度、冲击、弯曲试验,研究焊接电流电压及层间温度对焊缝组织及弯曲性能的影响。结果表明:两种焊接工艺参数下的焊缝组织均由奥氏体和析出相组成,采用较大焊接电流电压及不控制层间温度工艺的焊缝中出现明显的液化裂纹,热影响区组织中出现粒状贝氏体,采用较小焊接电流电压工艺的热影响区组织为板条马氏体。两种焊接工艺参数下的焊接接头拉伸、冲击、硬度试验均合格,采用较大焊接电流电压工艺,焊接接头的冲击值略低,热影响区的硬度值较低,接头塑性较差,在外力作用下裂纹沿着热影响区扩展导致弯曲断裂。采用小电流电压值焊接接头的塑性良好,弯曲试验合格。
Using small heat input,9 Ni steel were welded by arc welding with different welding parameters. The microstructure of welded joints were observed,and the tensile,bending,impact,hardness test on weld joints were conducted to study the effects of welding current,voltage and interlayer temperature on the microstructure and bending properties of welded joint. The results show that microstructure of the welded seam is mainly composed of austenite and precipitated phase,there are obvious liquefaction cracks in the welded seam with high welding current and voltage and without controlling the interlayer temperature,and granular bainite is found in the HAZ,the microstructure is composed of lath martensite with low welding current and voltage. The tensile,impact and hardness tests of the welded joints are all qualified with the two welding parameters. The impact energy,plasticity of the welded joints are slightly lower and poor and the hardness values of the HAZ is smaller with high welding current and voltage,and the crack propagates along the heat affected zone and leads to bending fracture with external stress. The welded joints with low current and voltage have good plasticity and qualified bending test.
Using small heat input,9 Ni steel were welded by arc welding with different welding parameters. The microstructure of welded joints were observed,and the tensile,bending,impact,hardness test on weld joints were conducted to study the effects of welding current,voltage and interlayer temperature on the microstructure and bending properties of welded joint. The results show that microstructure of the welded seam is mainly composed of austenite and precipitated phase,there are obvious liquefaction cracks in the welded seam with high welding current and voltage and without controlling the interlayer temperature,and granular bainite is found in the HAZ,the microstructure is composed of lath martensite with low welding current and voltage. The tensile,impact and hardness tests of the welded joints are all qualified with the two welding parameters. The impact energy,plasticity of the welded joints are slightly lower and poor and the hardness values of the HAZ is smaller with high welding current and voltage,and the crack propagates along the heat affected zone and leads to bending fracture with external stress. The welded joints with low current and voltage have good plasticity and qualified bending test.
引文
[1] Takahiro Kimura,AkinOhmori,Osamu Tanigawa. Properties of high tuoughness 9%Ni heavy sextion steel plate and its applicability to 200000kl LNG storage tanks[J]. Kawasaki Steel Technical Report,1999,40(5):72-79.
[2] Keun Yoon,Jae Hoon Kin,Kyu Taek Shim. Mechanical characteristies of 9%Ni steel welded joint for LNG storagetank attcryogenic[J]. WorldScientific,2012(6):355-360.
[3]崔忠圻,覃耀春.金属学与热处理[M].北京:机械工业出版社,2007:253.
[4]江伯鸿,李鹏兴,马逸伟,等.低碳低合金钢中粒状贝氏体的断裂特性[J].上海冶金,1980,2(1):43-47.
[5]孟根巴根,马成勇,彭云,等.热输入对9Ni钢焊接接头组织及低温冲击性的影响[J].焊接学报,2010,31(6):71.
[6]中国机械工程学会焊接学会.焊接手册第2卷[M].北京:机械工业出版社,2007:133-134.
[2] Keun Yoon,Jae Hoon Kin,Kyu Taek Shim. Mechanical characteristies of 9%Ni steel welded joint for LNG storagetank attcryogenic[J]. WorldScientific,2012(6):355-360.
[3]崔忠圻,覃耀春.金属学与热处理[M].北京:机械工业出版社,2007:253.
[4]江伯鸿,李鹏兴,马逸伟,等.低碳低合金钢中粒状贝氏体的断裂特性[J].上海冶金,1980,2(1):43-47.
[5]孟根巴根,马成勇,彭云,等.热输入对9Ni钢焊接接头组织及低温冲击性的影响[J].焊接学报,2010,31(6):71.
[6]中国机械工程学会焊接学会.焊接手册第2卷[M].北京:机械工业出版社,2007:133-134.